Apparatus for continuous reaction of high-viscous materials

ABSTRACT

An apparatus for continuously treating a high-viscosity material. A vessel has two spiral agitating blades arranged substantially horizontally and in side-by-side relation therein. Neither has a central supporting shaft, and each has a plurality of scraping blades projecting outwardly close to the inside surface of the wall of the vessel. The agitating blades intermesh with each other when the blades are rotated in opposite directions for scraping substantially all of the viscous material on the adjacent side and bottom wall of the vessel off such wall.

United States Patent Inamura et a1. 5] Feb. 8, 1972 [54] APPARATUS FORCONTINUOUS 2,506,101 5/1950 Oltz ..416/176 X REACTION OF HIGH v scous2,570,864 10/1951 Rowlson. ...259/D1G. 13 MATERIALS 3,064,908 11/1962Hjelte ..259/ 104 X 3,125,968 3/1964 Baker ..259/D1G. 12 [72] Inventors:Seiichl lnamura; Yusuke Kondo; Mlnoru Akita; Kenichi Cl u "i, a of 00m,FOREIGN PATENTS OR APPLICATIONS Japan 645,765 9/1962 Italy ..259/ 178 R[73] Assignee: Toyo Boseki Kabushiki Kaisha, on] a 569,381 7/1958 Belgum Japan Primary Examiner-Walter A. Scheel 22 Filed; 3, 19 9 AssistantExaminer-Alan 1. Cantor Attorney-Wenderoth, Lind & Ponack [2l] Appl.N0.: 813,209

[57] ABSTRACT [30] Foreign Application Priority Data An apparatus forcontinuously treating a high-viscosity material. A vessel has two spiralagitating blades arranged sub- Apr. 6, 1968 Japan ..43/23021 stamianyhorizontally and in Side by side relation therein Neither has a centralsupporting shaft, and each has a plurality [52] US. Cl. ..259/104, 259/6of scraping blades projecting outwardly close to the. inside Sun [51]Int. Cl. ..B0lf 7/08 f of the W3 f the vesSeL The agitating Hadeshum-mesh 6,21,41, each other when the blades are rotated in opposite D1316- 1 1 directions for scraping substantially all of the viscousmaterial 416/176 on the adjacent side and bottom wall of the vessel offsuch wall. [56] References Cited 6 Claims, 5 Drawing Figures UNITEDSTATES PATENTS 1,370,764 3/1921 Popkess ..l ..259/178 R 3 r 1 I S 8 I cr I 1 1 1 1 11/ r I a PAIENIEBFEB 8 m2 3.640.509

sum 1 or 2 BY vfl g a a ATTORNEYS PAIENIED EB" 8, I972.

SHEET 2 OF 2 FIG.5

SEIICHI INAMURA, YUSUKE KONDO,

' MINORU AKITA AND KENICHI CHIKANARI,

I nvenlor kluduma'ill 0J2 Attorney 5 APPARATUS FOR CONTINUOUS REACTIUNOF HIGH- VISCOUS MATERIALS This invention relates to an apparatus forthe continuous treatment (e.g., polymerization or concentration) ofhighviscous material. More particularly, this invention relates to anapparatus for the continuous treatment of high-viscous material whereinefficient agitation and high surface area renewal or generation areaccomplished.

In an apparatus for treating high-viscous material, for example, in anapparatus for conducting the final stage of polymerization orpolycondensation in the production of a film or film-forming polyesterwhere the reaction mass is highly viscous liquid material, the materialmust be well agitated so that local overheating and degradation areprevented and the surface of the reaction mass is constantly renewed tofacilitate the removal of volatile byproducts of the polymerization.Further, in order to obtain constant or uniform residence time of thereaction mass in the vessel there should be no such place where thereaction material stays as deposited or adhered.

In order to meet with these requirements, various reaction apparatushave been suggested. However, each of them has various disadvantages andthere has been no fully satisfactory one.

Therefore an object of this invention is to provide an apparatus for thecontinuous treatment of high-viscous material wherein the viscousmaterial is continuously and effectively agitated.

Another object of this invention is to provide an apparatus of the typedescribed above wherein the surface of the reaction mass is constantlyrenewed in order to facilitate the escape of volatile byproducts.

Still another object of this invention is to provide an apparatus of thetype mentioned above wherein the residence time is kept substantiallyconstant or uniform throughout the reaction mass.

Other objects, features and advantages of this invention will beapparent from the following description.

Briefly, this invention provides an apparatus comprising a vessel withmechanical agitating means which comprises at least two sets of anagitator in the form of a central-shaftless screw or spiral-shapedagitating blade arranged substantially horizontally and having aplurality of scraper plates projecting outwardly therefrom to be closeto the inner wall of at least a lower half of the vessel, the agitatorsbeing so substantially horizontally arranged that, when rotated inopposite directions, they intermesh with each other and substantiallyall of the reaction mass on or adjacent the side and bottom inner wallof the vessel is scrapped by the scraper plates.

It has been usual or conventional that an agitator of this kind has acentral supporting shaft which is driven. It has been found that viscousmaterial will deposit on and/or remain staying (stagnate) around thecentral shaft so that no uniform residence time of the reaction materialin the reaction vessel can be attained. Thus, according to thisinvention, there is provided no central supporting shaft in the agitatorso that the above difficulty is not seen. The spiral agitating blade ofthis invention may be weak in the mechanical strength and therefore itis preferable to reinforce the blade with a plurality of supporting barsextending through the blade in the axial direction.

When only one such spiral or screw-type agitating blade is provided,there is formed so-called bridge of the viscous material between theadjacent revoluting portions so that stagnation of the material willoccur. According to this invention, a plurality set of such agitatingblades are arranged in parallel so as to intermesh but not touch witheach other so that the bridge" which may be formed in one agitatingblade is broken by the corresponding revoluting portion on theneighboring agitating blade which moves into the space wherein the abovebridge" is formed. These agitating blades are rotated in oppositedirections, In order to further reduce the bridge, it is preferable toincrease the pitch of the spiral agitating blade toward the outlet ofthe reaction vessel.

The scraping plates are attached at intervals on the spiral blade. Eachscraping plate extends radially outwardly from the rotating blade to bevery close to the inner wall of the vessel with a very small clearance,for example, 5 mm. or less so as to scrape off the reaction materialadhered or deposited on the inner wall.

The reaction material is moved from the feed end to the discharge end ofthe vessel. This can be achieved, for example, by mounting the agitatingblades and/or scraping plates at a proper angle. If desired, this mayalso be effected by slightly inclining the vessel.

Since the material deposited on the wall of the upper part of the vesseldrops or falls due to the gravity, it is not always necessary topositively scrape it off, although such scraping is preferable. Usuallyit is sufficient that the reaction material on the wall of the lowerhalf of the vessel is scraped by the scraping plates. However, in anycase, it is necessary that the width and interval of the scraping platesare such that, upon one complete rotation of the agitating blades, anyportion of the wall of the lower half of the vessel is scraped by anyone of the scraping plates.

By the above arrangement according to this invention local overheatingand local thermal degradation of the material or polymer can beprevented and the mixing of the reaction material in the axial directionis kept minimum so that a homogeneous reaction or polymerimtion productcan be obtained within a short time.

The apparatus of the present invention is particularly useful forconducting the final polycondensation stage in the production of a highviscous polymer such as polyethylene terephthalate or any othercopolymerized polyester (e.g., polyethylene isoterephthalate).

The invention will be explained in more detail by referring to theaccompanying drawings wherein:

FIG. 1 is a side elevation of a part of a spiral agitating bladeembodying the present invention;

FIG. 2 is a schematic longitudinal section, in side elevation, of anapparatus embodying the invention;

FIG. 3 is a schematic plan view of an apparatus of FIG. I, with partsomitted and in secton;

FIG. 4 is a schematic cross section taken on the line IVIV of FIG. 2;and

FIG. 5 is a schematic cross section taken on the line VV of FIG. 2.

Referring to FIGS. 2 and 3, there is shown a horizontally arrangedelongated cylindrical reaction vessel fitted with a heating jacket 4 forcirculating a heating medium. A suitable heating medium is fed to thejacket 4 from an inlet 5 and discharged from an outlet 6. A reactionmaterial is fed to the vessel from a feeding inlet 7 and moved towardthe other end of the vessel and discharged from a discharge outlet 8.During the travel in the vessel the reaction (e.g., polycondensation)proceeds and gaseous byproducts are drawn off through an opening 9. Thecontent (reaction mass) in the vessel is continuously agitated. Areaction (polymerization) apparatus of this type is well known in theart so that no further detailed explanation thereabout will benecessary.

The important and novel feature of this invention is in a particularconstruction and arrangement of a mechanical agitating means to beexplained below.

According to the invention, there is used an agitating blade 1 which isin the form of spiral or screw as well shown in FIGS. 1 and 2. The blade1 is made of a strip or band which is twisted to form a continuous screwor spiral blade as a whole. The spiral agitating blade 1 has no centralsupporting shaft. In order to increase the mechanical strength of the Iagitating blade it is preferable to provide a plurality of supportingbars. Thus, in the embodiment shown, there are provided four supportingbars 3 horizontally extending in parallel to each other and through theblade 1. The agitating blade 1 is horizontally (the axis of rotationbeing horizontal) arranged within the vessel as shown. It is preferablethat the agitating blade I has a coarser pitch (as well shown in FIG. 2)toward the discharge end of the vessel.

On and along the spiral agitating blade 1 there are mounted a series ofscraping plates 2 at proper intervals. In the embodiment shown thescraping plates 2 are arranged with 90 interval between the adjacentplates 2 when seen in cross section as shown in FIGS. 4 and 5. Eachscraping plate 2 extends radially outwardly from the periphery of theblade 1 to be close to the inner wall (side and bottom wall) of thevessel with a small clearance, e.g., about 5 mm. or less therebetween.In the embodiment shown, the scraping plates 2 are mounted at an anglewith respect to the axis of rotation of the blade 1. However, it ispossible to arrange the scraping plates 2 in parallel to the axialdirection of rotation of the blade 1.

As shown in FIGS. 3, 4 and 5, there are provided two sets of suchagitating blade I. These two agitating blades 1 are arranged side byside and in parallel to each other as shown. The arrangement is suchthat the adjacent blades will interrnesh or not touch with each other.These two spiral blades 3 are rotated in opposite directions. Therefore,a bridge" of the viscous reaction material formed between adjacentrevolution sections, e.g., between a and b (HO. 3) on one agitatingblade is broken by a revolution section with the corresponding scrapingplate, e.g., c on the other agitating blade because the latter movesinto the space between a and b.

Further the width, angular position and density (number and interval)are such that when the scraping plates are projected on the wall alongthe line l-m (FIG. 3) they will span or cover substantially all of theline I-m. Therefore, when the blades with these scraping plates arerotated, substantially all of the inner wall (side and bottom wall) ofthe lower half of the vessel is subjected to scraping by the scrapingplates upon one rotation of the blades.

Each spiral agitating plate with supporting bars thereon is secured ateach end with a disc which is connected to a shaft or 10' which extendsoutwardly through the end wall of the vessel. These shafts l0 and 10 aredriven in opposite directions by a driving means (not shown).

As shown, the agitating blades are arranged adjacent the side and bottomwalls of the vessel. Usually, in unoperative state, at least one-thirdof the blades is exposed above the level of the reaction mass in thevessel. Thus, the upper wall of the vessel is not accessible by theblades or scraping blades, but this does not cause noticeable troublebecause any viscous mass which is deposited on the upper wall of thevessel would drop or fall by gravity.

The high-viscous material is slowly moved from the inlet end toward thedischarge end of the vessel without substantial intermixing in the axialdirection. In order to advance the viscous material, the spiral blades 1and/or scraping plates 2 may be set at a proper angle with respect tothe axial direction.

What we claim is:

1. An apparatus for continuously treating a high-viscous material whichcomprises a vessel within which are substantially horizontally arrangedin side-by-side relation at least two spiral agitating blades, eachhaving no central supporting shaft and having a plurality of scrapingplates projecting outwardly therefrom to be close to the inner wall ofthe vessel, the agitating blades, when rotated in opposite directions,intermesh with each other and substantially all of the viscous materialon and adjacent the side and bottom wall of the vessel is scraped off bythe scraping plates.

2. An apparatus as claimed in claim I wherein the pitch of eachagitating spiral blade is made coarser toward the discharge end of thevessel.

3. An apparatus as claimed in claim 1 wherein each scraping plateprojects radially outwardly from the blade, the clearance between theplate and wall of the vessel being about 5 mm. or less.

4. An apparatus as claimed in claim 1 wherein each blade is reinforcedby a plurality of supporting bars extending horizontally through theblade.

5. An apparatus as claimed in claim 1 wherein the scraping plates areset in parallel to the axis of rotation of the blade.

6. An apparatus as claimed in claim 1, wherein the scraping plates areset at an angle to the axis; or rotation of the blade.

1. An apparatus for continuously treating a high-viscous material whichcomprises a vessel within which are substantially horizontally arrangedin side-by-side relation at least two spiral agitating blades, eachhaving no central supporting shaft and having a plurality of scrapingplates projecting outwardly therefrom to be close to the inner wall ofthe vessel, the agitating blades, when rotated in opposite directions,intermesh with each other and substantially all of the viscous materialon and adjacent the side and bottom wall of the vessel is scraped off bythe scraping plates.
 2. An apparatus as claimed in claim 1 wherein thepitch of each agitating spiral blade is made coarser toward thedischarge end of the vessel.
 3. An apparatus as claimed in claim 1wherein each scraping plate projects radially outwardly from the blade,the clearance between the plate and wall of the vessel being about 5 mm.or less.
 4. An apparatus as claimed in claim 1 wherein each blade isreinforced by a plurality of supporting bars extending horizontallythrough the blade.
 5. An apparatus as claimed in claim 1 wherein thescraping plates are set in parallel to the axis of rotation of theblade.
 6. An apparatus as claimed in claim 1, wherein the scrapingplates are set at an angle to the axis of rotation of the blade.